Method for recycling spent lithium metal polymer rechargeable batteries and related materials

ABSTRACT

The method relates to a pyrometallurgical and hydrometallurgical process for the recovery and recycling of lithium and vanadium compounds from a material comprising spent rechargeable lithium batteries, particularly lithium metal gel and solid polymer electrolyte rechargeable batteries. The method involves providing a mass of the material, hardening it by cooling at a temperature below room temperature, comminuting the mass of cooled and hardened material, digesting with an acid its ashes obtained by incineration, or its solidified salts obtained by molten salt oxidation, or the comminuted mass itself, to give a mother liquor, extracting vanadium compounds from the mother liquor, separating heavy metals and aluminium therefrom, and precipitating lithium carbonate from the remaining solution.

TECHNICAL FIELD

This invention relates to a method for recovering and recycling, bymeans of a pyrometallurgical and hydrometallurgical process, lithium andvanadium compounds from spent lithium metal solid and gel polymerrechargeable batteries. More particularly, the invention is concernedwith the recovery of vanadium and lithium in the form of vanadiumpentoxide (V₂O₅) and lithium carbonate (Li₂CO₃) from lithium metal solidand gel polymer electrolyte batteries, scraps therefrom and productsused to produce them.

BACKGROUND ART

Despite the importance of strategic materials used into the fabricationof lithium secondary batteries, only few industrial processes weredeveloped commercially to recycle specifically spent lithium batteries,both primary and secondary. Actually, at present only three majorcompanies have developed commercial recycling processes for theneutralization and/or recovery of valuable by-products from spentlithium batteries and one is always developing at the pilot scale. Todaythe leading lithium battery recycler in the U.S. is Toxco, Inc. which isbased in Anaheim, Calif. Toxco processes lithium batteries at itsrecovery plant located at Trail, British Columbia, Canada. Toxcooperates a cryogenic process that is described in U.S. Pat. Nos.5,345,033 and 5,888,463 and which is capable of recycling about 500tonnes per year of spent lithium batteries. A major part of these arehigh performance batteries used as back-up power sources by the US Army(e.g., torpedoes, missiles). Hence numerous chemicals are recycledtogether without selective sorting (e.g., Li/SO₂, Li/SOCl₂, Li-Ion,lithium thermal batteries, and lithium reserve batteries). Essentially,the TOXCO process involves reducing the reactivity by lowering thetemperature using cryogenic liquids such as nitrogen or argon. Thefrozen batteries are then immersed under a large volume of aqueouscaustic solution made of sodium hydroxide and sodium carbonate. In thisbath, the still frozen battery cases are crushed. Active cell materials,such as lithium, react to release hydrogen and heat. Under these harshconditions, hydrogen ignites burning all flammable organic solvents. Atthe end of the process, cobalt and lithium carbonate, and in a lesserextent, paper and plastics, carbon black, and metal scrap are alsorecovered as secondary by-products. Lithium carbonate is purified byelectrodialysis and sold by a subsidiary of Toxco, LithChemInternational. However the TOXCO process is not specifically appropriateto the recycling of lithium metal solid and gel polymer electrolytebatteries because it focuses on alkaline solutions for dissolution anddoes not focus on the particular vanadium chemistry.

The second company is BDT Inc. formerly Battery Destruction Technologywhich is located in Clarence, N.Y. BDT specializes in the destruction ofhazardous wastes, particularly spent lithium batteries. The currentprocessing capacity is about 350 tonnes per year of both spent lithiumbatteries and lithium metallic scrap. The process involved which isdescribed in U.S. Pat. No. 4,647,928 consists in crushing the spentbatteries under an alkaline aqueous solution of sodium hydroxide with aswing type hammer mill. The resulting sludge is clarified by sievingthrough a coarse screen, solid wastes are removed by filtration andrecovered for disposal and landfilling, while the alkaline filtrate ispH adjusted and redirected to the mill. Unfortunately, this processwhich only intended to neutralize hazardous materials does not alloweasy separation and recovery of valuable by-products such as lithium andvanadium compounds.

The third company is Sony Electronics Inc. which, in close collaborationwith Sumitomo Metal Mining Company, has developed a process specificallydevoted to recovering cobalt oxide from its own spent Li-Ion batteriesused in electronic devices, such as laptop computers, camcorders,digital cameras, and cellular phones. The process involves thecalcination of spent cells and utilizes the cogeneration resulting fromburning electrolytes. It is capable of recovering cobalt oxide with asufficiently high quality to reuse the latter directly in thefabrication of new Li-Ion batteries, and the metallic scrap consists ofsecondary by-product, such as copper and stainless steel. Thistechnology is well established and recycling of spent lithium-ion cellsis today performed in Japan with a current processing capacity of120–150 tonnes per year. Improvement to this process is currentlyperformed in a pilot plant that is located in the US at Dothan, Ala.,with a R&D current capacity of 150 kg per year. However, theSony-Sumitomo process was specifically intended to recover only cobaltoxide from Lithium-Ion batteries and cannot be applied to the lithiummetal solid and gel polymer technology. Finally, several recentprocesses for the recovery of both cathodic materials and lithium fromcell materials used in Li-Ion secondary batteries were also developedbut were not implemented industrially. Finally the four following novelprocesses designed by Canon (U.S. Pat. No. 5,882,811), Kabushiki KaishaToshiba (U.S. Pat. No. 6,120,927), Tokyo Shibaura Electric Co. (U.S.Pat. No. 6,261,712),. and Merck Patent GmbH (EP 1056146), are allrelated to reclamation and recycling of lithium ion batteries. Inconclusion, none of the above processes are devoted specifically to thetreatment of lithium metal gel and solid polymer electrolyte batteriesfor recovering both lithium and vanadium therefrom.

Lithium metal polymer batteries, designated under the common acronymLMPB, are promising rechargeable power sources especially developed bythe Applicant for automotive applications, such as hybrid electricvehicles (HEV), and fully electric vehicle (EV), and the stationarymarket, such as electric power utilities, telecommunications, etc. Thebasic electrochemical system of these secondary batteries is made of ananode consisting of an ultra-thin lithium metal foil, a solid copolymerelectrolyte containing a lithium salt, a cathode comprising insertionlithium vanadium oxide compounds, and a carbon coated aluminium currentcollector. Owing to its thin film design, the electrochemical cell (EC)exhibits both high gravimetric (270 Wh/kg) and volumetric energy (415Wh/kg) densities. An ultimate chemical analysis expressed in massfraction of a typical electrochemical cell is presented in the followingTable 1.

TABLE 1 Ultimate chemical composition of an EC Chemical element Massfraction Carbon 28.383 wt % Oxygen 25.562 wt % Vanadium 16.612 wt %Aluminium 11.049 wt % Lithium 10.222 wt % Hydrogen  3.879 wt % Fluorine 2.540 wt % Sulphur  1.438 wt % Nitrogen  0.315 wt %

However, in view of to their content of strategic cell materials, highenergy density, and elevated chemical reactivity, spent lithium metalpolymer batteries represent hazardous wastes that could lead to majoreconomical, safety, and environmental issues in the commercialization oflarge lithium polymer batteries. Therefore, a large commercializationplant must provide for the recycling of these spent batteries in orderto neutralize and deactivate these hazardous wastes particularly lithiummetal, and lithium vanadium oxide due to their chemical reactivity,toxicity and corrosiveness, thereby ensuring a maximum plant health andsafety; it must also recycle all the strategic cell materials in orderto recover efficiently and in an economical manner the valuableby-products for decreasing production costs and preserving naturalresources from acute depletion. Finally such plant should avoid anyrelease of hazardous materials into the environment in order to fit inzero emission programs, developed by federal and governmentenvironmental agencies worldwide.

DISCLOSURE OF INVENTION

In accordance with the present invention there is provided a method ofrecovering and recycling lithium and vanadium compounds from a materialcomprising spent lithium metal solid polymer rechargeable batteries,and/or scraps therefrom and/or products used to produce said batteries,which comprises comminuting a hardened and cooled mass of said materialunder an inert atmosphere, treating the comminuted hardened cooled massto give a mother liquor containing dissolved vanadium salts and heavymetals, extracting vanadium pentoxide (V₂O₅) from the mother liquorseparating heavy metals, aluminium and other metallic impuritiestherefrom, and precipitating lithium carbonate from the remainingsolution.

Preferably, the mass of material is comminuted under a flow of liquefiedcryogenic gases such as liquid argon, liquid helium and liquid nitrogen.

In accordance with a preferred embodiment, the hardened cooled mass isobtained by hardening the mass of the material by cooling same to atemperature below about 273 K, such as between about 77 K and about273K, for example 85 K.

In accordance with another preferred embodiment, the method comprisesbatch incinerating the comminuted hardened cooled mass, and treating thecomminuted hardened cooled mass to give the mother liquor. Preferably,the comminuted hardened cooled mass is cooled and the gases producedthereby are scrubbed off before treating the cooled mass to give themother liquor.

Preferably, the liquor is obtained by digesting ashes and solid residuesobtained by batch incinerating the comminuted hardened cooled mass in anacid, such as HF, HCl, HBr, HI, HNO₃, H₃PO₄, H₂SO₄, HClO₄, HCOOH,CF₃SO₃H, or mixtures thereof. The preferred acid is H₂SO₄.

According to another embodiment, the mother liquor is obtained bydigesting the comminuted hardened cooled mass directly without priortreatment in an acid such as HF, HCl, HBr, HI, HNO₃, H₃PO₄, H₂SO₄,HClO₄, HCOOH, CF₃SO₃H, or mixtures thereof, H₂SO₄ being preferred, andseparating a mixture of inert gas and hydrogen to give the motherliquor.

In accordance with another embodiment, the method comprises heating thecomminuted hardened cooled mass under conditions and at a temperatureeffective to cause oxidation of the comminuted material and removinggases produced during the oxidation, before treating the cooled mass togive the mother liquor. Oxidation may be carried out by oxidizing and/orburning in a molten salt bath comprising a mixture of molten alkali andalkali-earth metals inorganic salts M_(n)X_(m) (with M=Li, Na, K, Rb,Cs, Be, Mg, Ca, Sr, Ba and X=F⁻, Cl⁻, Br⁻, I⁻, SO₄ ²⁻, NO₃ ⁻, CO₃ ²⁻,BO₃ ²⁻, PO₄ ³⁻), the comminuted hardened cooled mass at a temperatureeffective to cause destruction of the material, for example at atemperature between 500 K and 2000 K, and removing gases produced duringthe chemical reaction, before treating the cooled mass to give themother liquor.

In accordance with yet another embodiment, the mother liquor is obtainedby digesting the ground solidified salts from which the gases producedduring oxidation have been removed, in an acid such as HF, HCl, HBr, HI,HNO₃, H₃PO₄, H₂SO₄, HClO₄, HCOOH, CF₃SO₃H, or mixtures thereof, H₂SO₄being preferred, the mother liquor containing insoluble solids.

BRIEF DESCRIPTION OF DRAWINGS

The invention is illustrated by but is not limited to the annexeddrawing which illustrates preferred embodiments of the invention, and inwhich

FIGS. 1A, 1B, and 1C are flow sheets representing various steps of theprocess according to the invention.

MODES OF CARRYING OUT THE INVENTION

The following description should be read in conjunction with the annexeddrawings, which schematically summarize the steps of the variouspreferred embodiments.

Generally speaking, the invention relates to a method for the recoveryand recycling of lithium and vanadium compounds from spent rechargeablelithium batteries, particularly lithium metal gel and solid polymerelectrolyte rechargeable batteries, comprising at least one negativeelectrode active material, a separator, an electrolyte, one positiveelectrode active material, a current collector and a cell casing. Aftermechanical dismantling of the casing and providing a mass of cooled andhardened material, the method involves a novel recycling process,consisting of digesting with an acid its ashes obtained by incineration,or its solidified salts obtained by molten salt extraction or thecomminuted mass itself to give a mother liquor. The process includes thesteps of mechanically dismantling the batteries to remove the metalcasing and the electric hardware as scrap, hardening of the soft cellmaterials by lowering the temperature of the free electrochemical cells(ECs) below ambient temperature, and comminuting the ECs into smallerpieces while in cold state before further processing. The process alsoincludes the further steps of treating the ground cell materials as isor their ashes obtained by incineration, or their solid salts producedafter molten salts oxidation (MSO). The ground cell materials, the ashesobtained after incineration, or solidified salts resulting from moltensalt oxidation are dissolved into an acid, during which the highlyreactive and hazardous spent lithium batteries are first of all reducedto inert materials exhibiting a lower chemical reactivity. Afterwards,the process involves collecting the solid, liquid and gaseous dischargesfrom the reactor, dissolving the solid and liquid discharges with anappropriate solvent and absorbing the gaseous effluents with an alkalinesolution, mixing the resultant wash streams, separating precipitatesformed from the mixed stream and neutralizing the remaining solution.Finally, the last step consists in recovering efficiently, safely, andin a relatively economical manner the valuable by-products such asvanadium and lithium compounds for reuse in the manufacture ofelectrochemical cells.

The first step consists in hardening the soft materials such as lithiummetal and polymer contained in the mass of spent ECs by coolingpreferably below 273 K. The freezing step is necessarily required inorder to render the soft materials contained into the electrochemicalcell such as metallic lithium and gel or solid polymers more brittle andto facilitate the comminution operation unit and also based on theArrhenius law for the kinetics rate constant to diminish the chemicalreactivity of hazardous cell components during handling.

Due to the fact that active cell materials are tightly encapsulated in apolymeric film, the hardened and frozen ECs must encounter a comminutionprocess in order to release the active materials and enhance theiractive surface area. In addition, due to the plastic nature of most ofthe cell materials, cryogenic shredding is the preferred technique amongthe numerous size reduction processes. For example, the combination of acryogenic fluid with a rotary cutting mill will harden soft cellmaterials to render them brittle and easy to grind, and ensure safeoperating conditions by maintaining an inert atmosphere around therotary cutting mill. Cryogenic shredding is normally performed using acutting mill with sharp knives made of tool steel or hard cementedcarbides preferably operating under a continuous flow of liquid argon.The cuttings produced are usually smaller than 1 millimeter. Oversizecuttings are removed by screening under argon and are recycled to thecutting mill. The resulting slurry comprising undersize cuttings andliquid argon, is continuously poured into an incineration vessel. Whenit is completely full, the reactor is then closed and connected to acompressed air supply for batch incineration of the shredded mass. Then,argon is recovered by evaporation as is well known to those skilled inthe art while releasing a mass of cool shredded spent ECs at the bottomof the reactor.

Batch incineration is preferably carried out in a vessel made of bulkheat resistant alloy (e.g., Hastelloy®-X, Inconel®-617). The reaction inthe reactor is initiated by heating up the spent mass. After reaching130° C., usually an exothermic and fast reaction takes place for fewseconds with a peak temperature around 1500 K. Afterwards, thecombustion or incineration which is conducted, usually takes place at atemperature above about 1000 K during 8 hours. The pressure is about 900to about 1500 kPa absolute. For incineration, hot air, pure oxygen, oroxygen enriched containing gas, is passed through the reactor andcombustion is maintained at sufficiently high temperature (1000 K), withminimum oxygen content in flowing gas until substantially all thecarbonaceous materials in the residues are incinerated leaving primarilyfree metals or metal oxides. It will be noted that the elevated gross orhigh heating value (HHV) of spent electrochemical cells, ranging from 16to 23 MJ/kg (determined according to the standard ASTM D240) dependingon the type, can be efficiently used to recover heat by cogeneration.During combustion, the off-gases produced leaving the reaction vesselwith excess air or oxygen are cooled by means of a heat exchanger andare directed through a dust collector, such as baghouses, highefficiency particulate filters, or an electrostatic separator in orderto remove entirely any entrained particulates, such as Li₂O, Al₂O₃ andV₂O₅. Then the dust free gas is directed to a wet scrubber containing aspent slacked lime solution (i.e., Ca(OH)₂) for absorbing all thehazardous gaseous effluents, such as CO₂, HF, and SO₂. These gases reactto form a sludge of harmless precipitates made of calcium carbonate(CaCO₃), calcium fluoride (CaF₂), and calcium sulphate di-hydrate(CaSO₄.2H₂O) chemically identical with the three naturally occurringminerals (i.e., calcite, fluorspar, and gypsum) (See Cardarelli,F.—Materials Handbook. A Concise Desktop Reference.—Springer Verlag,London, N.Y. (2001), pages 395–478). These solid inorganic compounds canbe easily removed by settling and drying, and used as by-products inindustrial minerals applications or are ready for safe disposal andlandfilling. Finally, the released gases passes through a highlyefficient catalytic converter to remove possible residual NO_(x). Thereleased-gases leaving the catalytic converter is very clean.

After completion of the incineration steps, both the ashes and theremaining solid residues are discharged from the bottom of theincinerator and are introduced with collected dust and particulates intoa stirred digestion tank. Digestion is carried out in a glass linedsteel vessel or made of any other corrosion resistant materials (e.g.,Alloy-20, Alloy 20 Cb, Hastelloy® C-276, zirconium and alloys, niobiumor tantalum clad steel). The digestion reaction is initiated by addinghot inorganic or organic acids such as HF, HCl, HBr, HI, HNO₃, H₃PO₄,H₂SO₄, HClO₄, HCOOH, CF₃SO₃H, or a mixture of them, but sulphuric acid30 wt % % H₂SO₄ is preferred. The dimensionless operating acid ratio(the so-called ‘acid number’), i.e., ratio of mass of sulphuric acid tothe mass of ashes and solid residues is selected in order to (i)introduce an amount of acid at least equal but preferably greater thanthe stoichiometric amount required for neutralizing all the cell activematerials, and (ii) use the amount of acid required to absorb completelyall the heat generated preventing any thermal runaways and maintainingthe bath below the maximum temperature allowed in the process. Theexothermic reaction wherein lithium sulphate is formed increasestemporarily the temperature to 110–120° C. Nevertheless, to maintain aproper operating internal temperature during two hours, internalheating, such as thermowell, heating coil, jacketed walls, or externalcirculating fluid heating is provided with a tubular or plate heatexchanger. After complete dissolution of soluble by-products containingfor example Al, Al₂O₃, Li₂O, V₂O₅ and completion of side reactions(i.e., gas evolution, and heat generation), the solution containing alsosludge of insoluble material is pumped with a positive displacement pumpand cooled to room temperature. Then, the remaining insoluble solids areremoved by hydrocycloning or centrifugation and finally filtration usinga filterpress equipment. The filtration cake after washing and drying islandfilled.

The mother liquor and rinsing solutions that contain all the valuablevanadium and lithium are adjusted if necessary to pH below 1 withconcentrated sulphuric acid. Afterwards, a small amount of an oxidizingchemical such as chlorine, oxygen, ozone, sulfur dioxide, Caro's acids(H₂SO₅ and H₂S₂O₈) alkali-metals chlorates MClO₃, or permanganates MMnO₄(with M=Li, Na, K), or hydrogen peroxide, is carefully added to theheated solution (80° C.), or also an electrochemical oxidation isperformed in order to oxidize entirely all vanadium (IV) and (II)cations to pentavalent vanadium (V) giving at low pH a yellow solutionmade of vanadyl (V) sulphate (VO₂)₂SO₄. Oxidizing salts with lithiumcation or hydrogen peroxide are preferred reagents because they do notintroduce additional foreign elements and impurities in the solution.Actually these foreign cations or anions could render the ultimaterecovery of sufficiently pure chemicals economically unfeasible. Thenthe liquor is concentrated to obtain a molarity of vanadium (V) above200 mol.m⁻³. After completion, cooling down the mother liquor to 293 K,a cold solution of lithium hydroxide, LiOH, or also aqueous ammonia 28wt % NH₄OH is added until reaching pH=2 where flocculation of thehydrated red-brown precipitate of vanadium pentoxide (V₂O₅.250H₂O)occurs. The gelatinous precipitate is then separated by settling andfiltration, it is carefully washed, dewatered, and dried at 200° C. Inorder to recover V₂O₅, the calcinate must be fired above the meltingpoint of V₂O₅. The cooled black molten mass of pure V₂O₅ is then crushedand ground in a ball mill to produce a fine powder passing a 200 Tylermesh sieve. The oversize particles are recycled to the mill.

The previous filtrate is mixed with washing solutions and adjusted topH=2 by adding conc. H₂SO₄. The traces of heavy metals coming fromsolder, wiring (i.e., Cu²⁺, Pb²⁺, Sn²⁺) are removed by common cathodicelectrodeposition onto a steel, nickel, copper, or zirconium cathodeunder galvanostatic conditions with a constant cathodic current densityof 200 A.m⁻² and using an efficient dimensionally stable anode forevolving oxygen in acidic media (i.e., DSA®-O₂) such as Ti/IrO₂, butpreferably Nb/IrO₂ or Ta/IrO₂ (See Cardarelli, F.—Materials Handbook. AConcise Desktop Reference.—Springer Verlag, London, N.Y. (2001), pages328–331). Other methods can also include a separation using solventextraction or ion exchange resins techniques.

The purified solution obtained after removal of heavy metals is mixedwith washing solutions and concentrated by evaporation. Then, aftercooling down the mother liquor to 20° C., a cold solution of lithiumhydroxide, LiOH, or an aqueous ammonia 28 wt % NH₄OH is added untilreaching pH about 5 where flocculation of the gelatinous aluminiumhydroxide (Al(OH)₃) occurs. The precipitate is then separated bysettling and filtration. The carefully washed, dewatered, driedprecipitate is then calcinated and ready for use or disposal.

The purified lithium sulphate liquor obtained after extracting aluminiumtherefrom is mixed with washing solutions, concentrated by evaporationup to 650 kg.m⁻³ Li₂SO₄, adjusted to pH about 8 by adding lithiumhydroxide (LiOH), and warmed up to 100° C. Then carbon dioxide, CO₂ isbubbled, or ammonium carbonate (NH₄)₂CO₃ is added to precipitate lithiumcarbonate Li₂CO₃ which is separated by filtration. The precipitate iswashed and dried. The remaining liquor containing ammonium sulphate isstored for disposal.

As an alternative embodiment, instead of pouring the slurry obtained byshredding with a rotary cutting mill in an incineration vessel it iscontinuously poured into a digestion reaction vessel made of glass linedsteel or made of any other corrosion resistant materials (e.g.,Alloy-20, Alloy 20Cb, Hastelloy® C-276, zirconium and alloys, niobium ortantalum clad steel). The reactor is then closed and argon is recoveredby evaporation while releasing a mass of cool shredded ECs at the bottomof the reactor.

The digestion reaction is initiated by adding hot inorganic or organicacids such as HF, HCl, HBr, HI, HNO₃, H₃PO₄, H₂SO₄, HClO₄, HCOOH,CF₃SO₃H, or a mixture of them, but sulphuric acid 30 wt % H₂SO₄ at 80°C. is preferred. The dimensionless operating acid ratio (the so-called‘acid number’), i.e., ratio of mass of sulphuric acid to the mass ofspent ECs is selected in order to: (i) introduce an amount of acid atleast equal but preferably greater than the stoichiometric amountrequired for neutralizing all the cell active materials, and (ii) usethe amount of acid required to absorb completely all the heat generatedpreventing any thermal runaways and maintaining the bath below themaximum temperature allowed in the process. The exothermic reactionwherein lithium sulphate is formed increases temporarily the temperatureto 110–120° C. Nevertheless, to maintain a proper operating internaltemperature during one hour, internal heating, such as thermowell,heating coil, jacketed walls, or external circulating fluid heating isprovided, such as a tubular or plate heat exchanger are required. Aftercomplete dissolution of soluble by-products containing for example Al,Al₂O₃, Li₂O, V₂O₅ and completion of side reactions (i.e., hydrogen gasevolution, and heat generation), the solution also containing sludge ofinsoluble material is pumped with a positive displacement pump such as adiaphragm, a Moyno® or Delasco pump and cooled to room temperature.Then, the remaining insoluble solids are removed by hydrocycloning orcentrifugation and finally filtration using a filterpress equipment. Thefiltration cake after washing and drying is landfilled.

Extraction of vanadium, removal of heavy metals, and aluminium andlithium extraction are carried out in the same manner as in the firstembodiment.

In the third embodiment, instead of batch incinerating the shreddedmass, the latter is subject to batch oxidation performed in a moltensalt bath.

Batch molten salt oxidation (MSO) is employed and performed in areaction vessel made of corrosion and heat resistant alloy (e.g.,Hastelloy®-X, Inconel®-617, nickel or copper clad steel, titanium andalloys, zirconium and alloys). The reaction is initiated by injectingthe spent shredded mass into a molten salt bath comprising a mixture ofmolten alkali and alkali-earth metals inorganic salts M_(n)X_(m) (withM=Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba and X=F⁻, Cl⁻, Br⁻, I⁻, SO₄ ²⁻,NO₃ ⁻, CO₃ ²⁻, BO₃ ²⁻, PO₄ ³⁻) at temperatures between 500 K–2000 K,preferably 1000 K. Usually an exothermic and fast reaction takes placefor few seconds with a peak temperature around 1500K. Afterwards, thetemperature is maintained constant at 1000K during 8 hours. It will benoted that the elevated gross or high heating values (HHV) of spent ECsranging from 16 to 23 MJ/kg depending on type can be efficiently used torecover heat by cogeneration. During oxidation, the acid gases generatedsuch as HF, CO₂, and SO₂, are scrubbed from waste and captured in themelt as fluoride, carbonate, and sulphate salts. Other off-gases leavingthe reaction vessel, such as CO, NO_(x) are cooled by means of a heatexchanger and directed through a dust collector, such as baghouses, highefficiency particulate filter, or electrostatic separator, in order toremove entirely any entrained particulates. Then the dusted off-gasesare directed to a wet scrubber. Finally, the off-gases pass through acatalytic converter. The off-gases leaving the catalytic converter isvery clean.

After completion of each molten oxidation steps, the bath is cooled downand solidified. The solid salt mass is then crushed inside the reactorby means of a jack hammer, and the resulting blocks are further groundin a gyratory crusher followed by ball milling. The powdered salty massis introduced with collected dust and particulates into a stirreddigestion tank. Digestion is carried out in a glass lined steel vesselor a vessel made of any other corrosion resistant materials (e.g.,Alloy-20, Alloy 20 Cb, Hastelloy® C-276, titanium and alloys, zirconiumand alloys, niobium or tantalum clad steel). The digestion reaction isinitiated by adding hot inorganic or organic acids such as HF, HCl, HBr,HI, HNO₃, H₃PO₄, H₂SO₄, HClO₄, HCOOH, CF₃SO₃H, or a mixture thereof, butsulphuric acid 30 wt % H₂SO₄ at 80° C. is preferred. In order, tomaintain a proper operating internal temperature during one hour,internal heating, such as thermowell, heating coil, jacketed walls, orexternal circulating fluid heating is provided with a tubular or plateheat exchanger. After complete dissolution of soluble by-productscontaining for example Al, Al₂O₃, Li₂O, V₂O₅ and completion of sidereactions (i.e., gas evolution, and heat generation), the solution alsocontaining sludge of insoluble material is pumped with a positivedisplacement pump such as Moyno® or Delasco pump and cooled to roomtemperature. Then, the remaining insoluble solids are removed byhydrocycloning or centrifugation and finally filtration using afilterpress equipment. The filtration cake after washing and drying arelandfilled.

Extraction of vanadium, removal of heavy metals and extraction ofaluminium and lithium are carried out similarly as in the firstembodiment.

EXAMPLES

The invention will now be illustrated by the following non-limitingexamples.

Example 1 Incineration of ECs and Digestion of Ashes

The first step consisted in rendering more brittle and easy to comminutea mass of one kilogram of spent electrochemical cells (ECs) having thechemical composition listed in Table 1. The electrochemical cellsexhibited various states of charge. Hardening occurred by immersing thespent ECs directly into liquid argon maintained at 85 K. Thedimensionless ratio, denoted r_(AE), is the mass of liquid argonrequired per unit mass of ECs and it was calculated by the followingequation listed below:

$r_{AE} = {\frac{m_{A\; r}}{m_{EC}} = \frac{c_{PEC} \cdot \left( {T_{EC} - T_{F}} \right)}{c_{{PA}\; r} \cdot \left( {T_{F} - T_{A\; r}} \right)}}$where m_(Ar) and m_(EC) are the masses expressed in kg of liquid argonand spent ECs respectively, c_(PAr), and c_(PEC) are the specific heatcapacities expressed in J.kg⁻¹.K⁻¹ of liquid argon and spent ECsrespectively, and T_(Ar), T_(EC), and T_(F) are temperatures expressedin kelvin of liquid argon, spent ECs, and the final temperature allowedafter immersion respectively. Using liquid argon at 85K and based on thefollowing experimental parameters : (i) an average temperature T_(E)around 260K of spent ECs which are stored in refrigerated warehouses,(ii) the specific heat capacities of liquid argon c_(PAr) of 1058J.kg⁻¹.K⁻¹ (Perry, R. H., and Green, D. W.—Perry's Chemical Engineers'Handbook 7^(th) ed.—McGraw-Hill, New York (1997) page 2–217) and c_(PEC)of spent ECs of 1619 J.kg⁻¹.K⁻¹, and (iii) the final allowed temperatureof the solid-liquid mixture maintained slightly below the boiling pointof argon (87.65K) at 87 K, the practical ratio selected was about 134.That is 134 kg of liquid argon (ca. 95 dm³) were used for 1 kg of ECs.In addition, owing to the lower density of spent ECs (1369 kg.m⁻³) thanthe density of liquid argon at 85K (1407 kg.m⁻³), the light spent ECswere introduced into the liquid argon using either a metallic screenbasket or an expanded or a perforated metal box containing the said cellmaterials in order to prevent hazardous floatation at the liquid-gasinterface. Due to the issue of ductile-to-brittle transition at lowtemperature, face centered cubic (fcc) metals and alloys such asaluminium alloy 6061-T6 and austenitic stainless steel grade AISI 316Lwere preferred and selected for designing components and vessels. Theresidence time in the Dewar flask was about 30 minutes. Then morebrittle, the hardened mass was directed to a shredder having knivesblades made of tungsten carbide (Pulverisette 25, Fritsch GmbH). Duringthe comminution operation, a continuous flow of liquid argon at 85 Kcirculates by gravity inside the shredding chamber maintainingsufficient hardness of the cell materials, and providing by evaporationan inert medium around the delaminated sheets. The final specificsurface area of shredded cell materials forming delaminated pieces wasmeasured equal to 1.5 m².kg⁻¹ compared to the initial value of 0.3m².kg⁻¹ with expected benefits for the reaction kinetics. The cuttingsproduced were smaller than about one millimeter. Oversize cuttings wereremoved with a stainless steel 316L wet vibrating screen with apertureof 12 Tyler meshes operated under a flow of liquid argon and directed tothe cutting mill operation. Mass yield during comminution was about 98wt %. The resulting cooled slurry (i.e., undersize delaminated cuttingsand liquid argon) was directly collected with a perforated ladle andpoured into a tubular incinerator. The tubular incinerator vessel hadboth walls and bottom of 2.54 cm thickness, a total length of 0.9144 m,an outside diameter of 30.48 cm with an actual capacity of about 45 dm³.The incinerator was made of annealed Inconel®-617. The incinerator wassafely designed according to the ASME Boiler and Pressure Vessels codein order to withstand the maximum pressure rise in the worst case ofthermal runaway related to sudden decomposition reaction of one kg ECswithout proper venting. When completely loaded, the reactor and itscover flange were tightly bolted together using a pure annealedgold-platted copper O-ring and connected to an air compressor at 1.5bars absolute pressure. Then, liquid and gaseous argon were gentlyremoved by displacement while releasing a mass of cool shredded spentECs inside the reactor. The reaction in the incinerator was initiated byheating up the incinerator retort into an electric heating oven madewith a Fibrothal® module with Kanthal® Al heating elements. A flow of 20(STP)dm³/min compressed dry air was maintained until completion of thereaction in order to facilitate total combustion of all the carbonaceousmaterials (e.g., carbon black and copolymer). Two thermocouples B-typerecorded both the inside and outer reactor surface temperature. Afterreaching 130° C., usually an exothermic and fast reaction occurs for fewseconds with a peak temperature around 1500 K. Afterwards, the externalheating was maintained constant at a temperature of about 1000 K during8 hours. During combustion, the off-gases produced leaving the reactionvessel were collected and cooled by means of a miniature shell and tubeheat exchanger made of stainless steel grade AISI 316L (Exergy Inc.) andwere directed through a high efficiency particulate filter in order toremove entirely any entrained particulates (i.e., Li₂O, Al₂O₃, V₂O₅).Then the dust free gas is directed to a wet scrubber containing a spentslacked lime solution (Ca(OH)₂) for absorbing all the hazardous gaseouseffluents (i.e., CO₂, HF, and SO₂). These gases reacted to form a sludgeof harmless precipitates made of calcium carbonate (CaCO₃), calciumfluoride (CaF₂), and calcium sulphate (CaSO₄). The solid compounds wereremoved by settling and dried. Finally, the released gas passed througha small catalytic converter. After completion of the incineration steps,the 711 grams of both ashes and solid residues having the ultimatechemical composition presented in Table 2 were discharged from theincinerator and introduced with collected dust and particulates into thestirred digestion reactor.

TABLE 2 Chemical analysis of ashes from incinerated cells Chemicalelement Mass fraction Vanadium pentaoxide (V₂O₅) 40.88 wt % Aluminiumsesquioxide (Al₂O₃) 30.33 wt % Lithium oxide (Li₂O) 28.79 wt %

The digestion reactor was made of a small jacketed glass-lined steelvessel with a capacity of 37.85 dm³ (LBO series from Tycon®) and a largebottom discharge. The digestion reaction was initiated by adding asolution of sulphuric acid at ambient temperature, after which it washeated to 80° C. The dimensionless physical quantity called theoperating acid ratio, denoted R_(O), i.e., the mass of acid to the massof both ashes and solid residues that can be currently used withouthaving thermal runaway issues but sufficient to neutralize all the cellactive materials is determined taking the greater value of both theneutralization and the safety acid ratio as listed below.R _(O)=max(R _(N) , R _(S))

The dimensionless quantity called the neutralization acid ratio, denotedR_(N), i.e., the mass of acid required to neutralize stoichiometricallyall active cell materials to the mass of both ashes and solid residueswas calculated using the following theoretical equation:

$R_{N} = {\frac{m_{acid}}{m_{ashes}} = {\frac{{MM}_{H_{2}{SO}_{4}}}{x_{acid}} \cdot \left\lfloor {\frac{x_{{Li2O} \cdot}}{{MM}_{{Li2}\; O}} + \frac{x_{V2O5}}{{MM}_{V2O5}} + \frac{3 \cdot x_{Al2O3}}{{MM}_{Al2O3}}} \right\rfloor}}$where x_(Li2O), x_(V2O5), and x_(Al2O3) are the dimensionless massfractions of lithium oxide, vanadium pentaoxide, and aluminium oxidepresent in the ashes and solid residues; where MM_(H2SO4), MM_(Li2O),MM_(V2O5), and MM_(Al2O3) are the molecular molar masses expressed inkg.mol⁻¹ of sulphuric acid, lithium oxide, vanadium pentaoxide, andaluminium oxide, and x_(acid) is the sulphuric concentration expressedin mass fractions. This neutralization acid ratio is based on the threefollowing chemical reactions schemes:Li₂O+H₂SO₄=Li₂SO₄+H₂O Δh=−10386 kJ.kg⁻¹ of Li₂OV₂O₅+H₂SO₄=(VO₂)₂SO₄+H₂O Δh=−1715 kJ.kg⁻¹ of V₂O₅Al₂O₃+3H₂SO₄=Al₂(SO₄)₃+3H₂O Δh=−719 kJ.kg⁻¹ Al₂O₃

However, for safety reasons especially for preventing thermal runaways,another dimensionless physical quantity must be introduced andcalculated, it is the safety acid ratio, denoted R_(S). It describes theratio of the mass of acid that can absorb all the heat generated by theexothermic reaction wherein vanadyl, aluminium and lithium sulphates areformed without reaching the maximum allowed temperature to the mass ofashes and solid residues. The safety acid ratio can be calculated usingthe following equation:

${Rs} = {\frac{m_{acid}}{m_{ashes}} = \frac{\left\lbrack {{\Delta\; h_{reaction}} - {c_{Pashes}\left( {T_{\max} - T_{ashes}} \right)}} \right\rbrack}{c_{Paicd}\left( {T_{\max} - T_{acid}} \right)}}$

-   -   with c_(Pacid)=x_(water).c_(pwater)+x_(H2SO4).c_(PH2SO4)        where m_(acid) and m_(ashes) are the masses expressed in kg of        acid and ashes respectively, □h_(reaction), the specific        enthalpy of the dissolution reaction in J.kg⁻¹, c_(PH2SO4),        c_(Pacid), c_(Pwater) and c_(Pashes) are the specific heat        capacities expressed in J.kg^(−l .K) ⁻¹ of concentrated        sulphuric acid, the sulphuric acid aqueous solution, water, and        ashes respectively, and T_(acid), T_(ashes), and T_(max), are        temperatures expressed in kelvin of the acid, the ashes, and the        maximum temperature allowed in the process. For instance, values        of neutralization and safety acid ratios are listed for several        sulfuric acid concentrations in Table 3 based on the chemical        composition of the ashes listed in Table 2.

TABLE 3 Neutralization, safety and operating acid ratios for ashes withseveral acid concentrations Battery grade Concentrated sulphuric Dilutedsulphuric acid acid sulphuric acid (98 wt %. (30 wt %. (20 wt %. H₂SO₄)H₂SO₄) H₂SO₄) Neutralization acid 2.09 6.82 10.23 ratio (R_(N)) Safetyacid ratio (R_(S)) 19.71 8.65 7.99 Operating acid ratio 20.00 10.0015.00 (R_(O))

Therefore, for safety and economical concerns a sulphuric acidconcentration of 30 wt %. H₂SO₄ was selected with an operating acidratio of about 10, that is 7.11 kg of acid (ca. 6 dm³) in our case.After completion of the exothermic dissolution, the operatingtemperature was maintained at 80° C. during 2 hours by heating thejacket. Mixing was obtained with a PTFE-coated impeller (IKA). Aftercomplete dissolution of solids (i.e., Al₂O₃, Li₂O, V₂O₅) and completionof side reactions (i.e., gas evolution, and heat generation), the bathacidity was adjusted to pH below 1 by adding concentrated sulphuric acid98 wt %. Afterwards, about 50 grams of lithium chlorate, LiClO₃ orconcentrated hydrogen peroxide H₂O₂ 30% vol. was carefully added to theheated solution (80° C.) in order to oxidize all vanadium (IV) and (III)cations to pentavalent vanadium (V) species. Practically, the additionof the oxidizing chemical continues until the deep blue solution istotally converted to a yellow solution containing all vanadium asvanadyl (V) sulphate (VO₂)₂SO₄. Then the liquor is concentrated byevaporation to a molarity of vanadium (V) above 200 mol.m⁻³concentration which was determined by UV-Vis spectrophotometry. Oncedigestion and oxidation completed the solution was bottom pumped into atank with a positive displacement pump such as PTFE diaphragm pump(George Fisher) and allowed to cool to ambient temperature. Then, thefew remaining insoluble solids were removed by hydrocycloning orcentrifugation and finally filtration using a filterpress equipment.Afterwards, lithium hydroxide solution or aqueous ammonia 28 wt % NH₄OHwas added until reaching pH=2 where flocculation of the hydratedred-brown precipitate of vanadium pentoxide (V₂O₅.250H₂O) occurs. Thegelatinous precipitate was separated by settling and filtration,carefully washed, dewatered, and dried at 200° C. In order to recoverV₂O₅, the calcinate was fired at 700° C. during 2 hours in anInconel®-617 crucible. The cooled black molten mass of pure V₂O₅ wasthen crushed and ground in a pebble mill with yttria stabilized zirconiaballs of 10 mm to produce a fine red powder which passes a 200 Tylermesh sieve. The final mass was 293 g with a purity of 98.5 wt %. V₂O₅.The oversize particles were recycled to the pebble mill. The previousfiltrate was mixed with washing solutions and adjusted to pH about 2 byadding concentrated acid at 98 wt %. H₂SO₄. The traces of heavy metals(i.e., Cu²⁺, Pb²⁺ Sn²⁺) were removed by common cathodicelectrodeposition achieved onto a zirconium cathode under galvanostaticconditions with a constant cathodic current density of 200 A.m⁻² andusing an expanded dimensionally stable anode for evolving oxygen inacidic media (i.e., DSA®-O₂) such as Ta/IrO₂ (30 g/m² IrO₂)(Magnetochemie B. V.). The electrolyzed solution was mixed with washingsolutions and concentrated by evaporation in a kettle. Then, aftercooling down the mother liquor to 20° C., lithium hydroxide solution oraqueous ammonia 28 wt % NH₄OH was added until reaching pH about 5 whereflocculation of the gelatinous aluminium hydroxide (Al(OH)₃) occurred.The precipitate was then separated by settling and filtration. Thewashed, dewatered, dried precipitate was calcinated into a mufflefurnace (Carbolite). The 205 grams obtained exhibited a purity of 98 wt%. The purified lithium sulphate liquor was mixed with washingsolutions, concentrated by evaporation up to 650 kg/m³ Li₂SO₄ measuredby flame spectrophotometry and adjusted to pH about 8 by adding lithiumhydroxide (LiOH), and warmed up to 100° C. Then by bubbling carbondioxide or adding ammonium carbonate (NH₄)₂CO₃, lithium carbonate Li₂CO₃precipitated and was separated by filtration. The precipitate was washedand dried. The 520 grams of Li₂CO₃ obtained exhibited a purity of 98 wt%. The remaining liquor containing ammonium sulphate was discarded.

Example 2 Direct Digestion of ECs

The first step consisted in rendering more brittle and easy to comminutea mass of one kilogram of spent electrochemical cells (ECs) having thechemical composition listed in Table 1. The electrochemical cellsexhibited various states of charge. The hardening occurred by immersingthe spent ECs directly into liquid argon maintained at 85 K. Thedimensionless ratio, denoted r_(AE), is the mass of liquid argonrequired per unit mass of ECs and it was calculated by the followingequation listed below:

$r_{AE} = {\frac{m_{A\; r}}{m_{EC}} = \frac{c_{PEC} \cdot \left( {T_{EC} - T_{F}} \right)}{c_{{PA}\; r} \cdot \left( {T_{F} - T_{A\; r}} \right)}}$Where m_(Ar) and m_(EC) are the masses expressed in kg of liquid argonand spent ECs respectively, c_(PAr) and c_(PEC) are the specific heatcapacities expressed in J.kg⁻¹.K⁻¹ of liquid argon and spent ECsrespectively, and T_(Ar), T_(EC), and T_(F) are temperatures expressedin kelvin of liquid argon, spent ECs, and the final temperature allowedafter immersion respectively. Using liquid argon at 85K and based on thefollowing experimental parameters: (i) an average temperature T_(E)around 260K of spent ECs which are stored in refrigerated warehouses,(ii) the specific heat capacities of liquid argon c_(PAr) of 1058J.kg⁻¹.K⁻¹ (Perry, R. H., and Green, D. W.—Perry's Chemical Engineers'Handbook 7^(th) ed.—McGraw-Hill, New York (1997) page 2–217) and c_(PEC)of spent ECs of 1619 J.kg⁻¹.K⁻¹, and (iii) the final allowed temperatureof the solid-liquid mixture maintained slightly below the boiling pointof argon (87.65K) at 87 K, the practical ratio selected was about 134.That is 134 kg of liquid argon (ca. 95 dm³) were used for 1 kg of ECs.In addition, owing to the lower density of spent ECs (1369 kg.m⁻³) thanthe density of liquid argon at 85K (1407 kg.m⁻³), the light spent ECswere introduced into the liquid argon using either a metallic screenbasket or an expanded or a perforated metal box containing the said cellmaterials in order to prevent the hazardous flotation at the liquid-gasinterface. Due to the issue of ductile-to-brittle transition at lowtemperature, face centered cubic (fcc) metals and alloys such asaluminium alloy 6061-T6 and austenitic stainless steel grade AISI 316Lwere preferred and selected for designing components and vessels. Theresidence time in the Dewar flask was about 30 minutes. Then morebrittle, the hardened mass was directed to a shredder having knivesblades made of tungsten carbide (Pulverisette 25, Fritsch GmbH). Duringthe comminution operation, a continuous flow of liquid argon at 85 Kcirculates by gravity inside the shredding chamber maintainingsufficient hardness of the cell materials, and providing by evaporationan inert medium around the delaminated sheets. The final specificsurface area of shredded cell materials forming delaminated pieces wasmeasured equal to 1.5 m².kg⁻¹ compared to the initial value of 0.3m².kg⁻¹ with expected benefits for the reaction kinetics. The cuttingsproduced were smaller than about one millimeter. Oversize cuttings wereremoved with a stainless steel 316L wet vibrating screen with apertureof 12 Tyler meshes operated under a flow of liquid argon and directed tothe cutting mill operation. Mass yield during comminution was about 98wt %. The resulting cooled slurry (i.e., undersize delaminated cuttingsand liquid argon) was directly collected with a perforated ladle andpoured into the digestion reactor.

The digestion reactor was made of a small jacketed glass-lined steelvessel with a capacity of 37.85 dm³ (LBO series from Tycon®) with alarge bottom discharge. The digestion reaction was initiated by adding asolution of sulphuric acid at ambient temperature then heated to 80° C.In order to prevent the hazardous flotation of lithium metal at thesurface of the bath which can cause severe explosion of the hydrogenevolved, the spent ECs was maintained at the bottom of the reactor usingan immersed and fine expanded metallic screen made of Hastelloys® C-276.The dimensionless quantity called the operating acid ratio, denotedR_(O), i.e., the mass of acid to the mass of spent ECs that can becurrently used without having thermal runaway issues but sufficient toneutralize all the cell active materials is determined taking thegreater value of both the neutralization and the safety acid ratio aslisted below.R _(O)=max (R _(N) , R _(S))

The dimensionless quantity called the neutralization acid ratio, denotedR_(N), i.e., the mass of acid required to neutralize stoichiometricallyall active cell materials to the mass of spent ECs was calculated usingthe following theoretical equation:

$R_{N} = {\frac{m_{acid}}{m_{ECs}} = {\frac{{MM}_{H_{2}{SO}_{4}}}{x_{acid}} \cdot \left\lfloor {\frac{x_{{Li} \cdot}}{2 \cdot {MM}_{L\; i}} + \frac{x_{V2O5}}{2 \cdot {MM}_{V2O5}} + \frac{3 \cdot x_{Al}}{2 \cdot {MM}_{Al}}} \right\rfloor}}$Where x_(Li), x_(V2O5), and x_(Al) are the dimensionless mass fractionsof the lithium metal, vanadium pentaoxide, and aluminium metal presentin the spent ECs. Where MM_(H2SO4), MM_(Li), MM_(V2O5), and MM_(Al) arethe atomic and molecular molar masses expressed in kg.mol⁻¹ of sulphuricacid, lithium metal, vanadium pentaoxide, and aluminium metal, andx_(acid) is the sulphuric concentration expressed in mass fractions.This neutralization acid ratio is based on the three following chemicalreactions schemes:2Li+H₂SO₄=Li₂SO₄+H₂ Δh=−44835 kJ.kg⁻¹ of LiV₂O₅+H₂SO₄=(VO₂)₂SO₄+H₂O Δh=−1715 kJ.kg⁻¹ of V₂O₅2Al+3H₂SO₄=Al₂(SO₄)₃+3H₂ Δh=−18402 kJ.kg⁻¹ Al

However, for safety reasons especially for preventing thermal runaways,another dimensionless physical quantity must be introduced andcalculated, it is the safety acid ratio, denoted R_(S). It describes theratio of the mass of acid that can absorb all the heat generated by theexothermic reaction wherein vanadyl, aluminium and lithium sulphate areformed without reaching the maximum allowed temperature to the mass ofspent ECs. The safety acid ratio can be calculated using the followingequation:

${Rs} = {\frac{m_{acid}}{m_{EC}} = \frac{\left\lbrack {{\Delta\; h_{reaction}} - {c_{PECs}\left( {T_{\max} - T_{E\; C}} \right)}} \right\rbrack}{c_{Pacid}\left( {T_{\max} - T_{acid}} \right)}}$

-   -   with c_(Pacid)=x_(water).c_(pwater)+x_(H2SO4).c_(PH2SO4)        Where m_(acid) and m_(EC) are the masses expressed in kg of acid        and spent ECs respectively, □h_(reaction), the specific enthalpy        of the dissolution reaction in J.kg⁻¹, c_(PH2SO4), c_(Pacid),        c_(Pwater) and C_(PEC) are the specific heat capacities        expressed in J.kg⁻¹.K⁻¹ of concentrated sulphuric acid, the        sulphuric acid aqueous solution, water, and spent ECs        respectively, and T_(acid), T_(ECs), and T_(max), are        temperatures expressed in kelvin of the acid, the spent ECs, and        the maximum temperature allowed in the digestion process. For        instance, values of neutralization and safety acid ratios are        listed for several sulphuric acid concentrations based on the        chemical composition of the ashes listed in Table 4.

TABLE 4 Neutralization, safety and operating acid ratios for spent ECswith several acid concentrations Concentrated Battery grade Dilutedsulphuric acid sulphuric acid sulphuric acid (98 wt %. (30 wt %. (10 wt%. H₂SO₄) H₂SO₄) H₂SO₄) Neutralization acid 1.51 4.95 14.85 ratio(R_(N)) Safety acid ratio (R_(S)) 46.85 30.11 9.50 Operating acid ratio50.00 32.00 15 (R_(O))Therefore, for safety and economical concerns and due to the size of thereactor vessels sulphuric acid concentration of 30 wt %. H₂SO₄ wasselected with a corresponding operating acid ratio of about 32, that is32 kg of acid (26 dm³) After completion of the exothermic dissolution,the operating temperature was maintained at 80° C. during 4 hours byheating the jacket. Due to explosion hazards related to hydrogenevolution, mixing was obtained with motor driven impeller byrecirculating and heating the acid with a diaphragm pump and a plateheat exchanger made of Hastelloy®-C-276 (Alfa Laval). After completedissolution of solids (i.e., Al₂O₃, Li₂O, V₂O₅) and completion of sidereactions (i.e., hydrogen gas evolution, and heat generation), the bathacidity was adjusted to pH below 1 by adding concentrated sulphuric acid98 wt %. Afterwards, about 50 grams of lithium chlorate, LiClO₃ orconcentrated hydrogen peroxide H₂O₂ 30 % vol. was carefully added to theheated solution (80° C.) in order to oxidize all vanadium (IV) and (III)cations to pentavalent vanadium (V) species. Practically, the additionof the oxidizing chemical continue until the deep blue solution istotally converted to a yellow solution containing all vanadium asvanadyl (V) sulphate (VO₂)₂SO₄. Then the liquor is concentrated byevaporation to a molarity of vanadium (V) above 200 mol.m⁻³concentration which was determined by UV-Vis spectrophotometry. Oncedigestion and oxidation completed the solution was bottom pumped into atank with a positive displacement pump such as PTFE diaphragm pump(George Fisher) and let cooled to ambient temperature. Then, the fewremaining insoluble solids were removed by hydrocycloning orcentrifugation and finally filtration using a filterpress equipment.Afterwards, lithium hydroxide solution or aqueous ammonia 28 wt % NH₄OHwas added until reaching pH about 2 where flocculation of the hydratedred-brown precipitate of vanadium pentoxide (V₂O₅.250H₂O) occurs. Thegelatinous precipitate was separated by settling and filtration,carefully washed, dewatered, and dried at 200° C. In order to recoverV₂O₅, the calcinate was fired at 700° C. during 2 hours in anInconel®-617 crucible. The cooled black molten mass of pure V₂O₅ wasthen crushed and ground in a pebble mill with yttria stabilized zirconiaballs of 10 mm to produce a fine red powder which passes a 200 Tylermesh sieve. The final mass was 290 g with a purity of 98.5 wt %. V₂O₅.The oversize particles were recycled to the pebble mill. The previousfiltrate was mixed with washing solutions and adjusted to pH about 2 byadding conc. H₂SO₄ 98 wt %. The traces of heavy metals (i.e., Cu²⁺, Pb²⁺Sn²⁺) were removed by common cathodic electrodeposition achieved onto azirconium cathode under galvanostatic conditions with a constantcathodic current density of 200 A.m⁻² and using an expandeddimensionally stable anode for evolving oxygen in acidic media (i.e.,DSA®-O₂) such as Ta/IrO₂ (30 g/m² IrO₂) (Magnetochemie B. V.). Theelectrolyzed solution was mixed with washing solutions and concentratedby evaporation in a kettle. Then, after cooling down the mother liquorto 20° C., lithium hydroxide solution or aqueous ammonia 28 wt % NH₄OHwas added until reaching pH about 5 where flocculation of the gelatinousaluminium hydroxide (Al(OH)₃) occurred. The precipitate was thenseparated by settling and filtration. The washed, dewatered, driedprecipitate was calcinated into a muffle furnace (Carbolite). The 204grams obtained exhibited a purity of 98 wt %. The purified lithiumsulphate liquor was mixed with washing solutions, concentrated byevaporation up to 650 kg/m³ Li₂SO₄ measured by flame spectrophotometryand adjusted to pH=8 by, adding lithium hydroxide (LiOH), and warmed upto 100° C. Then bubbling carbon dioxide or adding ammonium carbonate(NH₄)₂CO₃ lithium carbonate Li₂CO₃ precipitated and was separated byfiltration. The precipitate was washed and dried. The 518 grams ofLi₂CO₃ obtained exhibited a purity of 97.5 wt %. The remaining liquorcontaining ammonium sulphate was discarded.

Example 3 Molten Salt Oxidation of ECs and Digestion of Salts

The first step consisted to render more brittle and easy to comminute amass of one kilogram of spent electrochemical cells (ECs) having thechemical composition listed in Table 1. The electrochemical cellsexhibited various states of charge. The hardening occurred by immersingthe spent ECs directly into liquid argon maintained at 85 K. Thedimensionless ratio, denoted r_(AE), is the mass of liquid argonrequired per unit mass of ECs and it was calculated by the followingequation listed below:

$r_{AE} = {\frac{m_{A\; r}}{m_{EC}} = \frac{c_{PEC} \cdot \left( {T_{EC} - T_{F}} \right)}{c_{{PA}\; r} \cdot \left( {T_{F} - T_{A\; r}} \right)}}$Where m_(Ar) and m_(EC) are the masses expressed in kg of liquid argonand spent ECs respectively, c_(Par) and c_(PEC) are the specific heatcapacities expressed in J.kg⁻¹.K⁻¹ of liquid argon and spent ECsrespectively, and T_(Ar), T_(EC), and T_(F) are temperatures expressedin kelvin of liquid argon, spent ECs, and the final temperature allowedafter immersion respectively. Using liquid argon at 85K and based on thefollowing experimental parameters: (i) an average temperature T_(E)around 260K of spent ECs which are stored in refrigerated warehouses,(ii) the specific heat capacities of liquid argon c_(PAr) of 1058J.kg⁻¹.K⁻¹ (Perry, R. H., and Green, D. W.—Perry's Chemical Engineers'Handbook 7^(th) ed.—McGraw-Hill, New York (1997) page 2–217) and c_(PEC)of spent ECs of 1619 J.kg⁻¹.K⁻¹, and (iii) the final allowed temperatureof the solid-liquid mixture maintained slightly below the boiling pointof argon (87.65K) at 87 K, the practical ratio selected was about 134.That is 134 kg of liquid argon (ca. 95 dm³) were used for 1 kg of ECs.In addition, owing to the lower density of spent ECs (1369 kg.m⁻³) thanthe density of liquid argon at 85K (1407 kg.m⁻³), the light spent ECswere introduced into the liquid argon using either a metallic screenbasket or an expanded or a perforated metal box containing the said cellmaterials in order to prevent the hazardous flotation at the liquid-gasinterface. Due to the issue of ductile-to-brittle transition at lowtemperature, face centered cubic (fcc) metals and alloys such asaluminium alloy 6061-T6 and austenitic stainless steel grade AISI 316Lwere preferred and selected for designing components and vessels. Theresidence time in the Dewar flask was about 30 minutes. Then morebrittle, the hardened mass was directed to a shredder having knivesblades made of tungsten carbide (Pulverisette 25, Fritsch GmbH). Duringthe comminution operation, a continuous flow of liquid argon at 85 Kcirculates by gravity inside the shredding chamber maintainingsufficient hardness of the cell materials, and providing by evaporationan inert medium around the delaminated sheets. The final specificsurface area of shredded cell materials forming delaminated pieces wasmeasured equal to 1.5 m².kg−1 compared to the initial value of 0.3m².kg⁻¹ with expected benefits for the reaction kinetics. The cuttingsproduced were smaller than about one millimeter. Oversize cuttings wereremoved with a stainless steel 316L wet vibrating screen with apertureof 12 Tyler meshes operated under a flow of liquid argon and directed tothe cutting mill operation. Mass yield during comminution was about 98wt %. The resulting cooled slurry (i.e., undersize delaminated cuttingsand liquid argon) was directly collected with a perforated ladle andpoured into a tall reaction vessel made of Inconel® 617 containingalready the dry pellets of the pre-melted salts. The reactor is a 0.9144meter tall vessel with an 304.8 mm outside diameter and wall and bottomthickness of 25.4 mm. The normal salt load is 10 kg of a binary mixtureof potassium sulphate (K₂SO₄) and lithium sulphate (Li₂SO₄) having aneutectic composition. When completely loaded, the reactor and its coverflange were tightly bolted together using a pure annealed gold-plattedcopper O-ring and connected to an air compressor at 1.5 bars absolutepressure. Then, liquid and gaseous argon were gently removed bydisplacement while releasing a mass of cool shredded spent ECs insidethe reactor with pre-melted salt pellets. The molten salt oxidation(MSO) was initiated by heating up the crucible into an electric heatingoven made with a Fibrothal® module with Kanthal® Al heating elements. Aflow of 20 (STP)dm³/min compressed dry air was maintained until thecompletion of the reaction in order to facilitate the total combustionof all the carbonaceous materials (e.g., carbon black and copolymer).Two thermocouples B-type recorded both the inside and outer reactorsurface temperature. After reaching 130° C., usually an exothermic andfast reaction occurs for few seconds with a peak temperature around 1500K. Afterwards, the external heating was maintained constant totemperature about 1000 K during 6 hours. During combustion, theoff-gases produced leaving the reaction vessel were collected and cooledby means of a miniature shell and tube heat exchanger made of stainlesssteel grade AISI 316L (Exergy Inc.) and were directed through a highefficiency particulate filter in order to remove entirely any entrainedparticulates (i.e., Li₂O, Al₂O₃, V₂O₅). Then the dust free gas isdirected to a wet scrubber containing a spent slacked lime solution(Ca(OH)₂) for absorbing all the hazardous gaseous effluents (i.e., CO₂,HF, and SO₂). These gases reacted to form a sludge of harmlessprecipitates made of calcium carbonate (CaCO₃), calcium fluoride (CaF₂),and calcium sulphate (CaSO₄). The solid compounds were removed bysettling and dried. Finally, the released gas passed through a smallcatalytic converter. After completion of the incineration steps, thesolidified salt mass was demolded and discharged from the reactor andthen crushed with a small jack hammer to small chunks. Solids wereintroduced with collected dust and particulates into the stirreddigestion reactor.

The digestion reactor was made of a small jacketed glass-lined steelvessel with a capacity of 37.85 dm³ (LBO series from Tycon®) with alarge bottom discharge. The digestion reaction was initiated by adding asolution of diluted sulphuric acid at ambient temperature then heated to80° C. For safety and economical concerns a sulphuric acid concentrationof 10 wt %. H₂SO₄ was selected with an operating acid ratio of about 2,that is 20 kg of acid. After completion of the dissolution, theoperating temperature was maintained at 80° C. during 1 hours by heatingthe jacket. Mixing was obtained with a PTFE-coated impeller (IKA). Aftercomplete dissolution of solids and completion of side reactions, thebath acidity was adjusted to pH below 1 by adding concentrated sulphuricacid 98 wt %. Afterwards, about 50 grams of lithium chlorate, LiClO₃ orconcentrated hydrogen peroxide H₂O₂ 30% vol. was carefully added to theheated solution (80° C.) in order to oxidize all vanadium (IV) and (III)cations to pentavalent vanadium (V) species. Practically, the additionof the oxidizing chemical continue until the deep blue solution istotally converted to a yellow solution containing all vanadium asvanadyl (V) sulphate (VO₂)₂SO₄. Then the liquor is concentrated byevaporation to a molarity of vanadium (V) above 200 mol.m⁻³concentration which was determined by UV-Vis spectrophotometry. Oncedigestion and oxidation completed the solution was bottom pumped into atank with a positive displacement pump such as PTFE diaphragm pump(George Fisher) and let cooled to ambient temperature. Then, the fewremaining insoluble solids were removed by hydrocycloning orcentrifugation and finally filtration using a filterpress equipment.Afterwards, lithium hydroxide solution or aqueous ammonia 28 wt % NH₄OHwas added until reaching pH about 2 where flocculation of the hydratedred-brown precipitate of vanadium pentoxide (V₂O₅.250H₂O) occurs. Thegelatinous precipitate was separated by settling and filtration,carefully washed, dewatered, and dried at 200° C. In order to recoverV₂O₅, the calcinate was fired at 700° C. during 2 hours in anInconel®-617 crucible. The cooled black molten mass of pure V₂O₅ wasthen crushed and ground in a pebble mill with yttria stabilized zirconiaballs of 10 mm to produce a fine red powder which passes a 200 Tylermesh sieve. The final mass was 293 g with a purity of 98.5 wt % V₂O₅.The oversize particles were recycled to the pebble mill. The previousfiltrate was mixed with washing solutions and adjusted to pH about 2 byadding conc. H₂SO₄ 98 wt %. The traces of heavy metals (i.e., Cu²⁺, Pb²⁺Sn²⁺) were removed by common cathodic electrodeposition achieved onto azirconium cathode under galvanostatic conditions with a constantcathodic current density of 200 A.m⁻² and using an expandeddimensionally stable anode for evolving oxygen in acidic media (i.e.,DSA®-O₂) such as Ta/IrO₂ (30 g/m² IrO₂) (Magnetochemie B.V.). Theelectrolyzed solution was mixed with washing solutions and concentratedby evaporation in a kettle. Then, after cooling down the mother liquorto 20° C., lithium hydroxide solution or aqueous ammonia 28 wt % NH₄OHwas added until reaching pH about 5 where flocculation of the gelatinousaluminium hydroxide (Al(OH)₃) occurred. The precipitate was thenseparated by settling and filtration. The washed, dewatered, driedprecipitate was calcinated into a muffle furnace (Carbolite). The 205grams obtained exhibited a purity of 98 wt %. The purified lithiumsulphate liquor was mixed with washing solutions, concentrated byevaporation up to 650 kg/m³ Li₂SO₄ measured by flame spectrophotometryand adjusted to pH=8 by adding lithium hydroxide (LiOH), and warmed upto 100° C. Then bubbling carbon dioxide or adding ammonium carbonate(NH₄)₂CO₃ lithium carbonate Li₂CO₃ precipitated and was separated byfiltration. The precipitate was washed and dried. The 520 grams ofLi₂CO₃ obtained exhibited a purity of 98 wt %. The remaining liquorcontaining ammonium sulphate was discarded. It must be understood thatthe invention is in no way limited to the above embodiments and thatmany changes may be brought about therein without departing from thescope of the invention as defined by the appended claims.

1. A method of recovering and recycling lithium and vanadium compoundsfrom a material comprising spent lithium metal gel and solid polymerelectrolyte rechargeable batteries, and/or scraps therefrom and/orproducts used to produce said batteries, which comprises providing amass of said material, hardening said mass by cooling at a temperaturebelow room temperature, comminuting said mass of cooled and hardenedmaterial, treating said comminuted mass with an acid to give an acidicmother liquor, extracting vanadium compounds from said mother liquor,separating heavy metals and aluminium therefrom and precipitatinglithium carbonate from remaining solution.
 2. Method according to claim1, which comprises comminuting said mass of hardened material under aflow of cryogenic liquefied gases.
 3. Method according to claim 2,wherein said mass of material is hardened by cooling it to a temperaturebetween 0 K and 298 K.
 4. Method according to claim 3, wherein said massof material is cooled to between 77 K and 273 K.
 5. Method according toclaim 4, wherein said mass of material is cooled to 85 K.
 6. Methodaccording to claim 1 or 2, which comprises batch incinerating saidcomminuted hardened cooled mass, and treating said comminuted hardenedcooled mass to give said mother liquor.
 7. Method according to claim 4,which comprises cooling said comminuted hardened cooled mass andscrubbing of gases produced thereby before treating same to give saidmother liquor.
 8. Method according to claim 6, wherein said liquor isobtained by digesting ashes and solid residues obtained by batchincinerating said comminuted hardened cooled mass in an acid.
 9. Methodaccording to claim 8, wherein said acid is selected from the groupconsisting of inorganic or organic acids.
 10. Method according to claim9 wherein said acid is selected from the group consisting of HF, HCl,HBr, HI, HNO₃, H₃PO₄, H₂SO₄, HClO₄, HCOOH, CF₃SO₃H, or mixtures thereof.11. Method according to claim 10, wherein said acid is sulphuric acid(H₂SO₄).
 12. Method according to claim 1, wherein said comminuted massis obtained by cryogenic comminution.
 13. Method according to claim 1,wherein said mother liquor is obtained by digesting the comminutedhardened cooled mass in an acid, and separating a mixture of inert gasand hydrogen to give said mother liquor.
 14. Method according to claim13, wherein said acid is selected from the group consisting of inorganicor organic acids.
 15. Method according to claim 14, wherein said acid isselected from the group consisting of HF, HCl, HBr, HI, HNO₃, H₃PO₄,H₂SO₄, HClO₄, HCOOH, CF₃SO₃H, or mixtures thereof.
 16. Method accordingto claim 15, wherein said acid is sulphuric acid H₂SO₄.
 17. Methodaccording to claim 1, which comprises heating said comminuted hardenedcooled mass under conditions and at a temperature effective to causebatch oxidation in a molten salt bath of said comminuted material andremoving gases produced during said oxidation, before treating saidcooled mass to give said mother liquor.
 18. Method according to claim17, wherein said oxidation is carried out by oxidizing and/or burningthe comminuted hardened cooled mass in a molten salt bath comprising amixture of molten alkali and alkali-earth metal inorganic salts, at atemperature effective to cause destruction of the comminuted material.19. Method according to claim 18, wherein said inorganic salts areselected from the group consisting of M_(n)X_(m) wherein M=Li, Na, K,Rb, Cs, Be, Mg, Ca, Sr, Ba and X=F⁻, Cl⁻, Br⁻, I⁻, SO₄ ²⁻, NO₃ ⁻, CO₃²⁻, BO₃ ²⁻, PO₄ ³⁻.
 20. Method according to claim 17, wherein saidtemperature is between 500 K and 2000 K.
 21. Method according to claim18, wherein said temperature is between 700 K and 1500 K.
 22. Methodaccording to claim 20, wherein said temperature is 1000 K.
 23. Methodaccording to claim 17, which comprises digesting the comminuted,hardened cooled mass from which said gases produced during saidoxidation have been removed, in an acid, said mother liquor containinginsoluble solids.
 24. Method according to claim 23, wherein said acid isselected from the group consisting of HF, HCl, HBr, HI, HNO₃, H₃PO₄,H₂SO₄, HClO₄, HCOOH, CF₃SO₃H, or mixtures thereof.
 25. Method accordingto claim 24, wherein said acid is sulphuric acid, H₂SO₄.
 26. Methodaccording to claim 8, wherein said mother liquor is treated to oxidizesubstantially entirely all vanadium (III) and (IV) cations topentavalent vanadium (V).
 27. A method of recovering and recyclinglithium and transitional metal compounds from a material comprisingspent lithium metal gel or solid polymer electrolyte rechargeablebatteries, and/or scraps therefrom and/or products used to produce saidbatteries, said method comprising the steps of: providing a mass of saidmaterial; neutralizing said mass by cooling at a temperature below roomtemperature; comminuting said mass of cooled material; treating thecomminuted mass with an acid to give an acidic mother liquor; extractingtransitional metal compounds from said acidic mother liquor; separatingaluminium from said acidic mother liquor and precipitating lithiumcarbonate from remaining solution.
 28. A method as defined in claim 27,wherein said transitional metal compounds is selected from a groupconsisting of phosphorus, iron, vanadium, manganese, nickel, titaniumand cobalt.
 29. A method as defined in claim 27, wherein mass of saidmaterial is cooled below 273 K.
 30. A method as defined in claim 29,wherein mass of said material is cooled below 243 K.
 31. A method asdefined in claim 27, further comprising the step of incinerating thecomminuted mass of cooled material prior to treating said comminutedmass with an acid.
 32. A method as defined in claim 31, furthercomprising the step of wet scrubbing of off-gases produced during theincineration step.
 33. A method as defined in claim 32, whereinoff-gases produced during the incineration step are filtered to removeentrained particulates.
 34. A method as defined in claim 31, whereinashes and solid residues of incineration are digested by reacting withan organic or inorganic acid.
 35. A method as defined in claim 27,further comprising the step of removing insoluble solid by-products byhydrocycloning or centrifugation and retaining soluble by-products toobtain said acidic mother liquor.
 36. A method as defined in claim 35,further comprising the step of adding an oxidizing chemical to saidacidic mother liquor to obtain a transitional metal sulphate.
 37. Amethod as defined in claim 27, further comprising the step of removingheavy metals from said acidic mother liquor.
 38. A method as defined inclaim 35, wherein said lithium carbonate is obtained by washing saidremaining solution and adding lithium hydroxide to adjust said remainingsolution to a pH of about 8, warming up said remaining solution, andadding carbon dioxide or ammonium carbonate to precipitate lithiumcarbonate which is separated by filtration.